In the last decade, molded plastic leaching chambers (also referred to as leaching conduits), sold under the registered U.S. trademark "Infiltrator", have met substantial commercial success. Examples of such type of chambers are shown in U.S. Pat. No. 4,759,661 to May and Nichols; and, in U.S. Pats. No. 5,017,041, No. 5,156,488 and 5,336,017 all to Nichols, all of which patents have an inventor and assignee in common herewith.
Generally, the commercial Infiltrator brand chambers and certain competitor products are arch shaped, have open bottoms, sloped perforated sides, and peak and valley corrugations running along the arch shape. Liquid introduced into the chamber disperses in the soil by passing through the open bottom and through the perforated sidewalls.
For economy of manufacture and distribution, typical chambers are identical, and nest readily for shipment. Chambers have opposing open ends adapted to enable one chamber to mate with other like chambers. Ends providing shiplap chamber joints strengthened by legs, tabs or other interlocks have been favored.
Typically, the molded chambers are placed end-to-end as an essentially straight string of units in a trench. Liquid flows through the chambers, from one to the next, by gravity. Thus, it is important that the units of a string of chambers will be placed in the earth so they have at most a very slight slope relative to the plane of the earth, from the first to the last, i.e., they must be "practially level". Thus, problems are presented when installations must be made on sloped land, such as a hillside, where the trench ought to follow a level contour line of the hill.
In the older designs of leaching chambers, for example in the type using spaced apart cast concrete galleries, the separate units can be put at angles to one another, and the non-parallel outlet and inlets of the galleries are connected by short lengths of pipe. The same approach can be used for the molded chambers. The trench in the soil is made in a jagged-curve, to follow the contour of the hillside and be practically level. Single chambers or short strings of chambers are fitted with end plates and connected as described just above. The disadvantage with this involves the use of endplates and pipe, which raises material and labor cost. And, longer trenches are needed to obtain the desired leaching area, presenting a problem on small lots.
One alternative for installing prior art molded chambers is to dig the trench straight and practically level. However, this can contravene good leaching practice since the trench necessarily becomes deep, and chambers are not placed near the surface of the earth where there is desirable oxygen transfer. In certain areas of the country, bedrock and ledge will make deep trenches infeasible. Another alternative is to provide an arch shape angle-adapter, or connector, interposing it between unaligned chambers. But, chamber ends must connect structurally, to best resist vertical loads during use. An adapter introduces the weakness of an additional joint or weakening point. And, having a separate component requires system installers to carry additional inventory.
Despite the continuing need, a better solution to the problem is required.